No, this statement is not entirely true. Both invertebrates and vertebrates can exhibit both innate (gained) behaviors and learned behaviors. Innate behaviors are instinctual and are present from birth, while learned behaviors are acquired through experience and exposure to the environment. While invertebrates may rely more on innate behaviors due to their simpler nervous systems, they can also learn and adapt their behavior based on their surroundings and interactions. Similarly, vertebrates can display both innate and learned behaviors depending on the species and context. Therefore, it is incorrect to generalize that invertebrates primarily show gained behavior and vertebrates primarily show learned behavior.
